Structures and methods for reducing stress in three-dimensional memory device

ABSTRACT

Embodiments of counter-stress structures and methods for forming the same are disclosed. The present disclosure describes a semiconductor wafer including a substrate having a dielectric layer formed thereon and a device region in the dielectric layer. The device region includes at least one semiconductor device. The semiconductor wafer further includes a sacrificial region adjacent to the device region, wherein the sacrificial region includes at least one counter-stress structure configured to counteract wafer stress formed in the device region.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority to PCT Patent Application No.PCT/CN2019/071190 filed on Jan. 10, 2019 which is incorporated herein byreference in its entirety.

TECHNICAL FIELD

The present disclosure generally relates to the field of semiconductortechnology, and more particularly, to a method for reducing stress insemiconductor wafers for forming a three-dimensional (3D) memory device.

BACKGROUND

Planar memory cells are scaled to smaller sizes by improving processtechnology, circuit designs, programming algorithms, and fabricationprocesses. However, as feature sizes of the memory cells approach alower limit, planar processes and fabrication techniques becomechallenging and costly. As such, memory density for planar memory cellsapproaches an upper limit. A three-dimensional (3D) memory architecturecan address the density limitation in planar memory cells.

BRIEF SUMMARY

Embodiments of three-dimensional (3D) NAND memory devices havingcounter-stress structures and methods for forming the same are describedin the present disclosure.

In some embodiments, a semiconductor wafer includes a substrate having adielectric layer formed thereon and a device region in the dielectriclayer. The device region includes at least one semiconductor device. Thesemiconductor wafer further includes a sacrificial region adjacent tothe device region, wherein the sacrificial region includes at least onecounter-stress structure configured to counteract wafer stress formed inthe device region.

In some embodiments, a semiconductor wafer includes an array of dies,where each die of the array of dies has a first type of wafer stress.The semiconductor wafer also includes sacrificial regions betweenadjacent dies of the array of dies and a plurality of semiconductorstructures formed in the sacrificial regions. Each semiconductorstructure includes high-stress material configured to produce a secondtype of wafer stress to counteract the first type of wafer stress.

In some embodiments, a method for forming a semiconductor wafer,includes forming a dielectric layer on a substrate and forming aplurality of semiconductor structures in a device region of thesemiconductor wafer. The plurality of semiconductor structures produce afirst type of wafer stress in the semiconductor wafer. The method alsoincludes forming a first plurality of openings in the dielectric layerand in the device region. The method further includes forming a secondplurality of openings in the dielectric layer and in a sacrificialregion that is adjacent to the device region. The method furtherincludes disposing high-stress material in the first and secondpluralities of openings, where the disposed high-stress materialproduces a second type of wafer stress in the semiconductor wafer tocounteract the first type of wafer stress.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are incorporated herein and form a partof the specification, illustrate embodiments of the present disclosureand, together with the description, further serve to explain theprinciples of the present disclosure and to enable a person skilled inthe pertinent art to make and use the present disclosure.

FIG. 1 illustrates a 3D NAND memory structure, in accordance with someembodiments of the present disclosure.

FIGS. 2-5 are cross-sectional views that illustrate exemplaryfabrication processes for forming counter-stress structures insacrificial regions of a semiconductor wafer, in accordance with someembodiments of the present disclosure.

FIGS. 6-7 are cross-sectional views that illustrate exemplarycounter-stress structures on a semiconductor wafer, in accordance withsome embodiments of the present disclosure.

FIGS. 8-10 are plan views that illustrate exemplary counter-stressstructures on a semiconductor wafer, in accordance with some embodimentsof the present disclosure.

FIG. 11 is a flow diagram illustrating exemplary methods for formingcounter-stress structures in sacrificial regions of a semiconductorwafer, in accordance with some embodiments of the present disclosure.

Embodiments of the present disclosure will be described with referenceto the accompanying drawings.

DETAILED DESCRIPTION

Although specific configurations and arrangements are discussed, itshould be understood that this is done for illustrative purposes only. Aperson skilled in the pertinent art will recognize that otherconfigurations and arrangements can be used without departing from thespirit and scope of the present disclosure. It will be apparent to aperson skilled in the pertinent art that the present disclosure can alsobe employed in a variety of other applications.

It is noted that references in the specification to “one embodiment,”“an embodiment,” “an example embodiment,” “some embodiments,” etc.,indicate that the embodiment described may include a particular feature,structure, or characteristic, but every embodiment may not necessarilyinclude the particular feature, structure, or characteristic. Moreover,such phrases do not necessarily refer to the same embodiment. Further,when a particular feature, structure or characteristic is described inconnection with an embodiment, it would be within the knowledge of aperson skilled in the pertinent art to effect such feature, structure orcharacteristic in connection with other embodiments whether or notexplicitly described.

In general, terminology may be understood at least in part from usage incontext. For example, the term “one or more” as used herein, dependingat least in part upon context, may be used to describe any feature,structure, or characteristic in a singular sense or may be used todescribe combinations of features, structures or characteristics in aplural sense. Similarly, terms, such as “a,” “an,” or “the,” again, maybe understood to convey a singular usage or to convey a plural usage,depending at least in part upon context.

It should be readily understood that the meaning of “on,” “above,” and“over” in the present disclosure should be interpreted in the broadestmanner such that “on” not only means “directly on” something but alsoincludes the meaning of “on” something with an intermediate feature or alayer therebetween, and that “above” or “over” not only means themeaning of “above” or “over” something but can also include the meaningit is “above” or “over” something with no intermediate feature or layertherebetween (i.e., directly on something).

Further, spatially relative terms, such as “beneath,” “below,” “lower,”“above,” “upper,” and the like, may be used herein for ease ofdescription to describe one element or feature's relationship to anotherelement(s) or feature(s) as illustrated in the figures. The spatiallyrelative terms are intended to encompass different orientations of thedevice in use or operation in addition to the orientation depicted inthe figures. The apparatus may be otherwise oriented (rotated 90 degreesor at other orientations) and the spatially relative descriptors usedherein may likewise be interpreted accordingly.

As used herein, the term “substrate” refers to a material onto whichsubsequent material layers are added. The substrate itself can bepatterned. Materials added on top of the substrate can be patterned orcan remain unpatterned. Furthermore, the substrate can include a widearray of semiconductor materials, such as silicon, germanium, galliumarsenide, indium phosphide, etc. Alternatively, the substrate can bemade from an electrically non-conductive material, such as a glass, aplastic, or a sapphire wafer.

As used herein, the term “layer” refers to a material portion includinga region with a thickness. A layer can extend over the entirety of anunderlying or overlying structure, or may have an extent less than theextent of an underlying or overlying structure. Further, a layer can bea region of a homogeneous or inhomogeneous continuous structure that hasa thickness less than the thickness of the continuous structure. Forexample, a layer can be located between any pair of horizontal planesbetween, or at, a top surface and a bottom surface of the continuousstructure. A layer can extend horizontally, vertically, and/or along atapered surface. A substrate can be a layer, can include one or morelayers therein, and/or can have one or more layer thereupon, thereabove,and/or therebelow. A layer can include multiple layers. For example, aninterconnection layer can include one or more conductor and contactlayers (in which contacts, interconnect lines, and/or vias are formed)and one or more dielectric layers.

As used herein, the term “nominal/nominally” refers to a desired, ortarget, value of a characteristic or parameter for a component or aprocess operation, set during the design phase of a product or aprocess, together with a range of values above and/or below the desiredvalue. The range of values can be due to slight variations inmanufacturing processes or tolerances. As used herein, the term “about”indicates the value of a given quantity that can vary based on aparticular technology node associated with the subject semiconductordevice. Based on the particular technology node, the term “about” canindicate a value of a given quantity that varies within, for example,10-30% of the value (e.g., ±10%, ±20%, or ±30% of the value).

As used herein, the term “3D memory device” refers to a semiconductordevice with vertically-oriented strings of memory cell transistors(i.e., region herein as “memory strings,” such as NAND strings) on alaterally-oriented substrate so that the memory strings extend in thevertical direction with respect to the substrate. As used herein, theterm “vertical/vertically” means nominally perpendicular to a lateralsurface of a substrate.

In some embodiments, a NAND string or a 3D memory device includes asemiconductor pillar (e.g., silicon pillar) that extends verticallythrough a plurality conductor/dielectric layer pairs. The plurality ofconductor/dielectric layer pairs are also referred to herein as an“alternating conductor/dielectric stack.” The conductor layer of thealternating conductor/dielectric stack can be used as a word line(electrically connecting one or more control gates). An intersection ofa word line and the semiconductor pillar forms a memory cell.Vertically-oriented memory strings require an electrical connectionbetween the conductors materials (e.g., word line plates or controlgates) and access lines (e.g., back end of line interconnection) so thateach of the memory cells along the memory strings or in the 3D memorydevice can be uniquely selected for writing or reading functions. Onemethod of forming electrical connections includes forming a staircasestructure on an alternating conductor/dielectric stack. The staircasestructure can be formed by repetitively etching the conductor/dielectriclayer stack using a mask layer formed over the dielectric stack layer,where each layer stack is also referred to as a “staircase layer” (or“SC layer”) of the staircase structure in the present disclosure. Adielectric layer is disposed on the staircase structure and openings areformed in the dielectric layer to expose each staircase layer.Electrical connections such as vias or lead wires are formed bydisposing conductive material in the openings and connecting to theconductive layer on each level of the staircase structure. Electricalconnections are also formed to connect peripheral circuitry to otherdevice/structures. Other layers and structures such as metal layers andvias are formed on the staircase structure and peripheral circuitry.

Thin film deposition, photolithography, etching processes are used toform various structures in semiconductor structures, such as disposingdielectric layers and forming interconnect structures. For example, in a3D NAND memory device, an alternating conductor/dielectric layer stackcan be fabricated by alternatingly disposing dielectric layers andreplacing a selection of the disposed dielectric layers with conductivelayers. However, when thin films having different coefficient of thermalexpansion (CTE) are stacked together, mismatch between thermal expansioncoefficients can lead to undesirable wafer stress. For example, thinfilms can be disposed using physical vapor deposition (PVD) processesthat are performed at a temperature above room temperature, and thedisposed thin films having mismatched CTEs contract at different speedsafter wafers are cooled down to room temperature. The variation oftemperature causes stress in the disposed thin films. In addition,intrinsic stress in thin films can arise due to several processes duringthin film deposition, for example, grain growth, grain boundaryrelaxation, shrinkage of grain boundary voids, phase transformations andprecipitation, vacancy annihilation, and other processes. Theseprocesses produce forces exerted onto the semiconductor structure andcause the semiconductor structure to “expand” or “shrink”, depending onthe direction of the force acting on the material, which respectivelyresults in tensile or compressive stress. Therefore, compressive stressand tensile stress are opposite types of wafer stress. In order toaccommodate these additional stress effects and reach a stable state,the film stack would bow itself up or down, depending whether theresultant stress is compressive or tensile. However, wafer bowing orwarpage is undesirable in semiconductor processing because a non-planarsurface can lead to non-uniform processing which in turn significantlyreduces product yield.

As the demand for higher storage capacity continues to increase, thenumber of vertical levels of the memory cells and staircase structuresalso increases. A semiconductor device having a large number of verticallevels, such as a 32-level or 64-level 3D NAND memory device, mayexperience wafer bowing and warpage that reduces product yield. Lowstress material can be used in semiconductor devices but selection ofthe low stress material is limited and often associated with complexprocesses and high cost. Alternatively, annealing processes can reducewafer stress but is often limited by thermal budgets of the devices.Accordingly, it is challenging to balance the manufacturing throughputand the process complexity/cost.

To address the above shortcomings, embodiments described herein aredirected to counter-stress structures for a 3D NAND memory device andfabricating methods of the same. In some embodiments, the counter-stressstructures can be semiconductor structures that are located insacrificial regions of a semiconductor wafer that act to counteractother stresses, such as stresses that may form in adjacent deviceregions. For example, the semiconductor structures can be trenchesfilled with high-stress material and formed in scribe lines betweenadjacent device regions. The counter-stress structures can reduceoverall stress of the semiconductor wafer by configuring the high-stressmaterial in sacrificial regions to generate stress that is the oppositetype of stress generated in the device regions. In some embodiments, thecounter-stress structures can be formed along the x-direction or they-direction in plan view. In some embodiments, the dimensions anddensity of counter-stress structures can be determined by the stresslevel of the semiconductor wafer.

The exemplary fabrication method for forming counter-stress structuresincludes forming openings in sacrificial regions of a semiconductorwafer containing an array of 3D NAND memory devices. In someembodiments, the sacrificial regions can be regions where no device isformed. In some embodiments, sacrificial regions can be within a die.For example, sacrificial regions can be a region within a die that nodevice is formed. High stress material is disposed in the openings andused to counter the stress formed by other structures on thesemiconductor wafer. In some embodiments, forming the openings anddepositing high stress material can be performed concurrently withforming openings for peripheral circuitry and disposing conductivematerial in the peripheral circuit openings, respectively, which in turnprovides the benefit of no additional masks or processes steps needed.

Various counter-stress structures described in the present disclosurecan provide benefits such as, among other things, reduced overall stressin 3D NAND memory devices without occupying device space, no additionalmasks or processing steps needed, and wide range of suitable high-stressmaterials. Therefore, counter-stress structures can reduce stress insemiconductor wafers, which in turn ensures and improves the performanceand yield of the 3D NAND memory devices.

Before describing contact pads in 3D NAND memory devices in detail, anexemplary 3D NAND flash memory device is illustrated in FIG. 1. Theflash memory device includes a substrate 101, an insulating layer 103over substrate 101, a tier of bottom select gate electrodes 104 overinsulating layer 103, and a plurality of tiers of control gateelectrodes 107 (e.g., 107-1, 107-2, and 107-3) stacking on top of bottomselect gate electrodes 104. Flash memory device 100 also includes a tierof top select gate electrodes 109 over the stack of control gateelectrodes 107, doped source line regions 120 in portions of substrate101 between adjacent bottom select gate electrodes 104, andsemiconductor channels 114 through top select gate electrodes 109,control gate electrodes 107, bottom select gate electrodes 104, andinsulating layer 103. Semiconductor channel 114 (illustrated by a dashedeclipse) includes a memory film 113 over the inner surface ofsemiconductor channel 114 and a core filling film 115 surrounded bymemory film 113 in semiconductor channel 114. The flash memory device100 further includes a plurality of bitlines 111 disposed on andconnected to semiconductor channels 114 over top select gate electrodes109. A plurality of metal interconnects 119 are connected to the gateelectrodes (e.g., 104, 107, and 109) through a plurality of metalcontacts 117. During device fabrication, metal interconnects 119 arealigned and connected to metal contacts 117. In some embodiments, metalcontacts 117 can be vias formed in insulating layers that are formedbetween adjacent tiers of gate electrodes. Insulating layers are notshown in FIG. 1 for simplicity. The gate electrodes can also be referredto as the word lines, which include top select gate electrodes 109,control gate electrodes 107, and bottom select gate electrodes 104.

In FIG. 1, for illustrative purposes, three tiers of control gateelectrodes 107-1, 107-2, and 107-3 are shown together with one tier oftop select gate electrodes 109 and one tier of bottom select gateelectrodes 104. Each tier of gate electrodes have substantially the sameheight over substrate 101. The gate electrodes of each tier areseparated by gate line slits 108-1 and 108-2 through the stack of gateelectrodes. Each of the gate electrodes in a same tier is conductivelyconnected to a metal interconnect 119 through a metal contact 117. Thatis, the number of metal contacts formed on the gate electrodes equalsthe number of gate electrodes (i.e., the sum of all top select gateelectrodes 109, control gate electrodes 107, and bottom select gateelectrodes 104). Further, the same number of metal interconnects isformed to connect to each metal contact 117.

For illustrative purposes, similar or same parts in a 3D NAND memorydevice are labeled using same element numbers. However, element numbersare merely used to distinguish relevant parts in the DetailedDescription and do not indicate any similarity or difference infunctionalities, compositions, or locations. Although using a 3D NANDdevice as an example, in various applications and designs, the disclosedstructure can also be applied in similar or different semiconductordevices to, e.g., reduce the leakage current between adjacent wordlines. The specific application of the disclosed structure should not belimited by the embodiments of the present disclosure. For illustrativepurposes, word lines and gate electrodes are used interchangeably todescribe the present disclosure. In various embodiments, the number oflayers, the methods to form these layers, and the specific order to formthese layers may vary according to different designs and should not belimited by the embodiments of the present disclosure. It should be notedthat the x-direction and y-direction illustrated in these figures arefor clarity purposes and should not be limiting.

Exemplary configuration and fabrication processes of counter-stressstructures including trenches filled with high-stress material aredescribed further in detail below with reference to FIGS. 2-11.Exemplary structures and fabrication processes shown in FIGS. 2-11 canbe directed to forming 3D NAND memory devices. The 3D NAND memorydevices can include word line staircase regions and counter-stresstrenches extending in any suitable direction such as, for example,positive y-direction, negative y-direction, positive x-direction,negative x-direction, and/or any suitable directions.

FIG. 2 illustrates a cross-sectional view of a portion of asemiconductor wafer that includes 3D NAND memory structures and openingsfor forming counter-stress structures, according to some embodiments.Semiconductor wafer includes a substrate 202 and a dielectric layer 211.Dielectric layer 211 includes a top surface 213 that is substantiallyplanar. 3D NAND memory structure 201 is formed in a device region 200 ofthe semiconductor wafer and trenches 252 are formed in a sacrificialregion 250 of the semiconductor wafer. Merely for ease of description,device region 200 and sacrificial region 250 are separated by boundary246. In addition, for ease of description, device region 200 thatincludes 3D NAND memory structure 201 can be divided into three regions:staircase region 210, active device region 220, and peripheral deviceregion 230. In some embodiments, device region 200 and sacrificialregion 250 can both be within a boundary of a semiconductor die. In someembodiments, device region 200 can be within a boundary of asemiconductor die while sacrificial region 250 can be outside of the dieboundary.

Substrate 202 can include any suitable material for forming a 3D NANDmemory structure. In some embodiments, substrate 202 can includesilicon, silicon germanium, silicon carbide, silicon on insulator (SOI),germanium on insulator (GOI), glass, gallium nitride, gallium arsenide,any suitable III-V compound material, and/or combinations thereof.Dielectric layer 211 can be formed using any suitable dielectricmaterial such as, for example, silicon oxide, silicon nitride, siliconoxynitride, and/or other suitable dielectric materials. The depositionof dielectric layer 211 can include any suitable methods such aschemical vapor deposition (CVD), physical vapor deposition (PVD),plasma-enhanced CVD (PECVD), sputtering, metal-organic chemical vapordeposition (MOCVD), atomic layer deposition (ALD), and/or combinationsthereof. Dielectric layer 211 can include one or more etch stop layersand are not illustrated for ease of description.

A plurality of conductor layer 234 and dielectric layer 236 pairs areformed in staircase region 210 and active device region 220. Activedevice region 220 can include functional semiconductor devices that arecommonly referred to as “active devices.” For example, active devicescan include transistors, diodes, and/or any suitable semiconductordevices. It is not required that an active device need to actually beoperating, but that it is one of a class of “active devices” capable ofbeing operated (e.g., can be turned on and off). The plurality ofconductor/dielectric layer pairs are also referred to herein as analternating conductor/dielectric stack 242. Conductor layers 234 anddielectric layers 236 in alternating conductor/dielectric stack 242alternate in the vertical direction. In other words, except the ones atthe top or bottom of alternating conductor/dielectric stack 242, eachconductor layer 234 can be adjoined by two dielectric layers 236 on bothsides, and each dielectric layer 236 can be adjoined by two conductorlayers 234 on both sides. Conductor layers 234 can each have the samethickness or have different thicknesses. Similarly, dielectric layers236 can each have the same thickness or have different thicknesses. Insome embodiments, alternating conductor/dielectric stack 242 includesmore conductor layers or more dielectric layers with different materialsand/or thicknesses than the conductor/dielectric layer pair. Conductorlayers 234 can include conductor materials including, but not limitedto, W, Co, Cu, Al, doped silicon, silicides, or any combination thereof.Dielectric layers 236 can include dielectric materials including, butnot limited to, silicon oxide, silicon nitride, silicon oxynitride, orany combination thereof.

3D NAND memory structure 201 further includes NAND strings 214 formed inactive device region 220 and include a plurality of control gates (eachbeing part of a word line). Each conductor layer 234 in alternatingconductor/dielectric stack 242 can act as a control gate for each memorycell of NAND string 214. Further, NAND strings 214 can include a selectgate 238 (e.g., a drain select gate) at an upper end and another selectgate 240 (e.g., a source select gate) at a lower end. As used herein,the “upper end” of a component (e.g., NAND string 214) is the endfurther away from substrate 202 in the z-direction, and the “lower end”of the component (e.g., NAND string 214) is the end closer to substrate202 in the z-direction. In some embodiments, select gates 238 and 240can include conductor materials including, but not limited to, W, Co,Cu, Al, doped silicon, silicides, or any combination thereof.

A peripheral device region 230 can be formed adjacent to active deviceregion 220. Peripheral device region 230 can include a plurality ofperipheral devices 206 formed on substrate 202, in which the entirety orpart of the peripheral device is formed in substrate 202 (e.g., belowthe top surface of substrate 202) and/or directly on substrate 202. Theperipheral devices 206 can include a plurality of transistors formed onsubstrate 202. Isolation regions and terminals 208 (e.g., a sourceregion, a drain region, or a gate of the transistor) can be formed insubstrate 202 as well.

In some embodiments, the peripheral device can include any suitabledigital, analog, and/or mixed-signal peripheral circuits used forfacilitating the operation of 3D NAND memory structure 201. For example,peripheral devices 206 can include one or more of a page buffer, adecoder (e.g., a row decoder and a column decoder), a sense amplifier, adriver, a charge pump, a current or voltage reference, or any active orpassive components of the circuits (e.g., transistors, diodes,resistors, or capacitors). In some embodiments, the peripheral device isformed on substrate 202 using complementary metal-oxide-semiconductor(CMOS) technology (also known as a “CMOS chip”).

3D NAND memory structure 201 further includes contact structures instaircase region 210, active device region 220, and peripheral deviceregion 230. The contact structures are formed to provide electricalconnections to devices embedded in substrate 202 and/or dielectric layer211. For example, 3D NAND memory device includes one or more word linecontacts in staircase region 210. Word line contacts can extendvertically within dielectric layer 211. Each word line contact can havean end (e.g., the lower end) in contact with a corresponding conductorlayer 234 in alternating conductor/dielectric stack 242 to individuallyaddress a corresponding word line of the array device.

Peripheral interconnect structures can also be formed above peripheraldevices 206 to transfer electrical signals to and from peripheraldevices 206. Peripheral interconnect structures can include one or morecontacts and conductor layers, each including one or more interconnectlines and/or vias. As used herein, the term “contact” can broadlyinclude any suitable types of interconnects, such as middle-end-of-line(MEOL) interconnects and back-end-of-line (BEOL) interconnects,including vertical interconnect accesses (e.g., vias) and lateral lines(e.g., interconnect lines).

To form word line contacts and peripheral interconnect structures,openings are first formed in dielectric layer 211 to expose thecorresponding word line of the array device and/or terminals 208 ofperipheral devices 206. For example, openings 212 are formed instaircase region 210 through dielectric layer 211 to expose one or moreconductor layers 234 of alternating conductor/dielectric stack 242.Similarly, openings 232 are formed in peripheral device region 230through dielectric layer 211 to expose terminals 208 of peripheraldevices 206. Openings 212 and 232 can be formed in the same fabricationstep (e.g., during the same patterning and etching processes) orrespectively formed in different fabrication steps, according to someembodiments. Openings 252 are formed in sacrificial region 250 forforming counter-stress structures. One or more openings 252 can extendinto dielectric layer 211, and in some embodiments, further extendinginto substrate 202. In some embodiments, openings 252 can havesubstantially the same depth or different depths. Width W and depth D ofopenings 252 can respectively determine the width and depth ofsubsequently formed counter-stress structures. In some embodiments,openings 252 can have a width W that is between about 0.1 μm and about0.5 μm. In some embodiments, openings 252 can have a depth D that isbetween about 4 μm and about 10 μm.

Openings 212, 232, and 252 can be formed using one or more patterningand etching processes. In some embodiments, openings 252 are formedusing patterning and etching processes that are the same as those usedto form openings 212 and/or openings 232. Such arrangement provides thebenefit of not requiring any additional photolithography masks orprocessing steps. In some embodiments, openings 252 are formed indifferent fabrication steps other than those used to form openings 212or openings 232. In some embodiments, the patterning process can includeforming a photoresist layer on dielectric layer 211, exposing thephotoresist layer to a pattern, performing post-exposure bake processes,and developing the photoresist layer to form a masking element includingthe resist. The masking element can protect regions of dielectric layer211, while one or more etch processes are used to form an opening indielectric layer 211. The etching process can be a reactive ion etch(RIE) process, a wet etching process, and/or other suitable process. Theetching process can continue until the underlying layer is exposed. Forexample, the etching process for forming openings 212 can continue untilthe conductor layers 234 are exposed. In some embodiments, the etchingprocess for forming openings 232 can continue until the underlyingterminals 208 are exposed. In some embodiments, the etching process forforming openings 252 can continue until the underlying substrate 202 isexposed. In some embodiments, openings 252 can be formed using a timedetching process where a nominal depth D of openings 252 is achieved bycontinuing the etching process for a specified time until a nominaldepth D is reached.

FIG. 3 illustrates a cross-sectional view of a portion of asemiconductor water after filling openings in device regions andsacrificial regions, in accordance to some embodiments of the presentdisclosure. As shown in FIG. 3, a layer of conductive material 310 isdisposed on the semiconductor wafer. For example, high-stress material310 is disposed in openings 212, 232, and 252. In some embodiments,high-stress material can be a material used to form deposited filmhaving internal film stress greater than about 1 Gpa. In someembodiments, high-stress material 310 completely fills openings 212,232, and 252 and overflows onto top surface 213 of dielectric layer 211,as illustrated in FIG. 3. In some embodiments, high-stress material 310partially fills opening 252. In some embodiments, openings 252 can befilled using a separate deposition process other than the depositionprocess used to fill openings 212 or 232. High-stress material 310 canbe any suitable high-stress material including, but not limited to,tungsten (W), cobalt (Co), copper (Cu), aluminum (Al), or anycombination thereof. High-stress material 310 can be used to counter thestress formed in structures in the device regions of the semiconductorwafer such that the overall stress in the semiconductor wafer isreduced. For example, if compressive stress is detected in thesemiconductor wafer due to structures such as 3D NAND memory structure201 or peripheral devices 206, high-stress material 310 can be materialthat provides tensile stress when formed in openings 252 to counter thecompressive stress and reduce the overall stress. Similarly, if tensilestress is detected in the semiconductor wafer due to structures such as3D NAND memory structure 201 or peripheral devices 206, high-stressmaterial 310 can be material that provides compressive stress whenformed in openings 252 to counter the tensile stress and reduce theoverall stress. High-stress material 310 can be a conductive materialsuch that openings 212 and 232 filled with high-stress material 310 canalso be used to provide electrical connection to the underlyingconductive structures. Tungsten is an example of high-stress materialthat also provides exceptional electrical conductivity. Disposingconductive high-stress material in openings 212, 232, and 252 canprovide the benefit of forming both the conductive structures in thedevice region and counter-stress structures in the sacrificial regionusing one fabrication step, without the need to use additional masks ordeposition steps. In some embodiments, the high-stress material can bedisposed using any suitable deposition method such as, for example, forexample, CVD, PVD, PECVD, sputtering, MOCVD, ALD, and/or combinationsthereof. In some embodiments, a conductive material disposed in openingsof the device region can be different from a high-stress materialdisposed in openings in the sacrificial region for formingcounter-stress structures, however, that would likely require more thanone deposition step and additional masks for photolithography process.In some embodiments, high-stress material disposed in openings 252 canbe formed using one or more materials including at least one high-stressmaterial. For example, a first high-stress material can be disposed inopenings 252 using any suitable deposition methods, and a secondhigh-stress material can be disposed on the first high-stress materialusing any suitable deposition methods. In some embodiments, at least oneof the first and second high-stress materials is a high-stress materialsuch as, for example, tungsten. In some embodiments, other layers suchas barrier layers, liners, can be disposed in the openings and are notillustrated for ease of description.

FIG. 4 illustrates a cross-sectional view of a portion of asemiconductor wafer after a planarization process is performed, inaccordance to some embodiments of the present disclosure. Aplanarization process can be used to remove excessive high-stressmaterial 310 from top surface 213 of dielectric layer 211 such that topsurfaces of high-stress material 310 filled in openings 212, 232, and252 are substantially level (e.g., coplanar) with top surface 213. Insome embodiments, the planarization process can be a chemical mechanicalpolishing process. After the planarization process, conductivestructures are formed in the openings of device region 200 andcounter-stress structures are formed in sacrificial region 250. Forexample, conductive structures 412 are formed in openings 212 ofstaircase region 210. Similarly, conductive structures 432 are formed inopenings 232 of peripheral device region 230. In some embodiments,conductive structures 412 can be contact wires and referred to as wordline contacts. Counter-stress structures 452 can be formed insacrificial region 250 after the planarization process. Although aplurality of counter-stress structures 452 are illustrated in FIG. 4,any suitable number of counter-stress structures can be used. In someembodiments, the suitable number of counter-stress structures depends onthe stress that is accumulated in the semiconductor water due tosemiconductor structures such as 3D NAND memory structure 201. In someembodiments, a greater amount of counter-stress material can be used toreduce a greater amount of stress. The greater amount of counter-stressmaterial disposed can be achieved through forming a greater number ofcounter-stress structures. In some embodiments, the greater amount ofcounter-stress material disposed can be achieved through formingcounter-stress structures with greater width W and/or depth D, aspermitted by fabrication limitations.

FIG. 5 illustrates a semiconductor wafer after lead wires are formed andelectrically connected to various conductive structures, in accordanceto some embodiments of the present disclosure. As shown in FIG. 5, adielectric layer 513 is disposed on planarized top surface 213 ofdielectric layer 211 and on top surfaces of conductive structures 412and 432. In some embodiments, dielectric layer 513 is also disposed ontop surfaces of counter-stress structures 452. Dielectric layer 513 canbe formed using any suitable dielectric material such as, for example,silicon oxide, silicon nitride, silicon oxynitride, and/or othersuitable dielectric materials. The deposition of dielectric layer 513can include any suitable methods such as CVD, PVD, PECVD, sputtering,MOCVD, ALD, and/or combinations thereof. Dielectric layer 513 caninclude one or more etch stop layers and are not illustrated for ease ofdescription.

Lead wires 519A-519C are formed in staircase region 210, lead wire 550is formed in active device region 220, and lead wires 539A-539C areformed in peripheral device region 230, in accordance to someembodiments. Each of the lead wires 519A-519C and 539A-539C can beelectrically connected to conductive structures 412 and 432,respectively. Lead wires 519A-519C and 539A-539C can be formed using anysuitable deposition, patterning, and etching processes. In someembodiments, lead wires 519A-519C and 539A-539C can be formed using anysuitable material such as, for example, tungsten, copper, silver,aluminum, cobalt, and/or combinations thereof. As shown in FIG. 5, leadwires 519A-519C can be aligned with underlying conductive structures 412and lead wires 539A-539C can be aligned with underlying conductivestructures 432 to provide electrical connectivity.

FIGS. 6-7 are cross-sectional views of portions of a semiconductor waferincluding peripheral structures and various counter-stress structures,according to some embodiments. FIGS. 6-7 respectively illustrateportions of semiconductor wafers 600 and 700 that includes substrate602, dielectric layer 611, a plurality of peripheral devices 606 formedin peripheral device regions 630A and 630B, counter-stress trenches 652and 752 formed in sacrificial region 650 that is between the peripheraldevice regions 630A and 630B. Peripheral devices 606 can include aplurality of transistors in substrate 602. Isolation regions andterminals 608 can be formed in substrate 602 as well. Conductivestructures 632 can be formed in dielectric layer 611 that provideelectrical connection to structures formed in peripheral device regions630A and 630B. Peripheral devices 606, terminals 608, and conductivestructures 632 can be respectively similar to peripheral devices 206,terminals 208, and conductive structures 432 described above in FIG. 5and are not described in detail here for simplicity. Sacrificial region650 is formed between adjacent peripheral device regions 630A and 630B.In some embodiments, adjacent peripheral device regions 630A and 630Bcan be portions of adjacent dies, respectively, and sacrificial region650 is formed between the adjacent dies. In some embodiments, portionsof sacrificial region 650 can be portions of adjacent dies. In someembodiments, the adjacent dies can include other structures such as 3DNAND memory devices in a device region. In some embodiments, sacrificialregion 650 can be a scribe line on wafer 600 or 700. Scribe lines arespaces between dies on a semiconductor wafer where a precision dicingsaw can cut through to safely separate the dies. Therefore, no devicesare formed in the scribe line region because the scribe line would besacrificed during the dicing process. Counter-stress structures formedin the scribe line can utilize the sacrificial scribe line region andreduce overall wafer stress. For example, counter-stress structures 652and 752 respectively illustrated in FIGS. 6-7 can be formed usinghigh-stress material that reduces wafer stress. The disposed high-stressmaterial can provide compressive or tensile stress for respectivelyreducing tensile or compressive stress in wafers 600 or 700.

The cross-sectional shapes and numbers of counter-stress structures canbe determined by the amount of stress accumulated in the semiconductorwafers. For example, a single counter-stress structure can be formed ineach scribe line. In some embodiments, two counter-stress structures canbe formed in each scribe line, as illustrated in FIGS. 6-7. In someembodiments, any suitable number of counter-stress structures can beused. Counter-stress structures can also have any suitablecross-sectional shape. For example, cross-sectional shape ofcounter-stress 652 illustrated in FIG. 6 can have a trapezoidal shapewith top width W₁ measured at the top of counter-stress structure 652and bottom width W₂ measured at the bottom of counter-stress structure652. As illustrated in FIG. 6, counter-stress structure 652 can have agreater width at the top than at the bottom of the structure, and suchconfiguration can provide the benefit of providing greater reducedstress towards the top of dielectric layer 611. In some embodiments,width W₁ can be in a range between about 0.1 μm and about 0.5 μm. Insome embodiments, width W₂ can be in a range between about 0.05 μm andabout 0.2.5 μm. In some embodiments, a top-to-bottom ratio R₁ of W₁ overW₂ can be between about 1.5 and about 2.5. For example, R₁ can be about2. In some embodiments, a depth D₁ of counter-stress structures 652 canbe in a range between about 4 μm and about 10 μm. In some embodiments,an angle α between top surface and sidewall surfaces of counter-stressstructure 652 can be in a range between about 90° and about 45°. Asillustrated in FIG. 7, counter-stress structure 752 can have a greaterwidth at the bottom than at the top of the structure, and suchconfiguration can provide the benefit of providing greater stresstowards the bottom of dielectric layer 611 or substrate 602. In someembodiments, width W₃ at the top of counter-stress structures 752 can bein a range between about 0.05 μm and about 0.25 μm. In some embodiments,width W₄ at the bottom of counter-stress structures 752 can be in arange between about 0.1 μm and about 0.5 μm. In some embodiments, atop-to-bottom ratio R₂ of W₃ over W₄ can be between about 0.4 and about0.7. For example, R₂ an be about 0.5. In some embodiments, a depth D₂ ofcounter-stress structures 752 can be in a range between about 4 μm andabout 10 μm. In some embodiments, an angle β between bottom surface andsidewall surfaces of counter-stress structure 652 can be in a rangebetween about 90° and about 45°.

FIGS. 8-10 are plan views that illustrate dies and exemplarycounter-stress structures on a semiconductor wafer, according to someembodiments. Counter-stress structures can be used to reduce waferstress in any suitable horizontal directions such as, for example, in anx-direction, a v-direction, or both. FIGS. 8-10 include an array of dies802 spaced equally from each other in the x-direction and y-direction.Dies 802 can include a plurality of device regions such as device region200 illustrated in FIGS. 2-5. For example, dies 802 can include 3D NANDmemory structures having staircase regions and active device regions.Dies 802 can also include peripheral device regions. The staircaseregions, active device regions, peripheral device regions, and othersuitable structures are not illustrated in FIGS. 8-10 for simplicity.The regions between dies 802 can be sacrificial regions such as scribelines. In some embodiments, sacrificial regions may be within dies 802and surrounding the device region. In some embodiments, any suitablenumber of counter-stress structures can be implemented in thesacrificial regions.

For example, FIG. 8 illustrates a single counter-stress structure 804formed between adjacent dies 802 and extending in the x-direction forreducing wafer stress generated along the y-direction. In someembodiments, more than one counter-stress structure 804 can be formed inthe scribe line. Counter-stress structures 804 can reduce wafer tensileor compressive stress along the y-direction. For example, structuresformed in the semiconductor wafer causes tensile stress (e.g., asschematically illustrated as tensile stress 803) that expands thesemiconductor wafer in the y-direction. Counter-stress structures 804formed along the x-direction can be formed using one or more high-stressmaterials that provide compressive stress (e.g., as schematicallyillustrated as compressive stress 805) along the y-direction that cancounter tensile stress 803 and result in reduced overall stress in thesemiconductor wafer. Similarly, structures formed in the semiconductorwater can cause compressive stress (e.g., as schematically illustratedas compressive stress 806) that compresses the semiconductor wafer inthe y-direction. Counter-stress structures 807 formed along thex-direction can be formed using one or more high-stress materials thatprovide tensile stress (e.g., as schematically illustrated as tensilestress 807) substantially along the y-direction that can counter tensilestress 803 and result in reduced overall stress in the semiconductorwafer.

FIG. 9 illustrates counter-stress structures 808 formed in scribe linesbetween adjacent dies 802 and extending in the y-direction. Functioningin a similar fashion as counter-stress structures 804 described in FIG.8, counter-stress structures 808 can reduce wafer compressive or tensilestress. Counter-stress structures 808 can be extending in they-direction and substantially reduce stress in the x-direction. Forexample, counter-stress structure 808 can be formed using high-stressmaterial providing compressive or tensile stress to reduce tensile orcompressive stress, respectively, in the x-direction.

FIG. 10 illustrates counter-stress structures 810 x and 810 y formed inscribe lines between adjacent dies 802 for substantially reducing waferstress in the x-direction and y-direction, respectively. In someembodiments, counter-stress structures 810 x can be formed usinghigh-stress material and are similar to counter-stress structures 808described in FIG. 9. In some embodiments, counter-stress structures 810y can be formed using high-stress material and are similar tocounter-stress structures 804 described in FIG. 8.

FIG. 11 is a flow diagram of an exemplary method 1100 of formingcounter-stress materials in semiconductor wafers, in accordance withsome embodiments of the present disclosure. This disclosure is notlimited to this operational description of method 1100. Rather, otheroperations are within the spirit and scope of the present disclosure. Itis to be appreciated that additional operations may be performed.Moreover, not all operations may be needed to perform the disclosureprovided herein. Further, some of the operations may be performedsimultaneously, or in a different order than shown in FIG. 11. In someimplementations, one or more other operations may be performed inaddition to or in place of the presently described operations. Forillustrative purposes, method 1100 is described to form counter-stressstructures illustrated in FIGS. 1-10, however, method 1100 is notlimited to these embodiments.

At operation 1102, a semiconductor wafer having device regions andsacrificial regions is formed, in accordance with some embodiments. Anexample of device regions on a semiconductor wafer can be a region on asubstrate that includes 3D NAND memory structure. Device regions caninclude a staircase region, an active device region, and a peripheraldevice region, such as staircase region 210, active device region 220,and peripheral device region 230, respectively, in FIG. 2. The substratecan include silicon, silicon germanium, silicon carbide, SOI, GOI,glass, gallium nitride, gallium arsenide, any suitable III-V compoundmaterial, and/or combinations thereof. An example of the substrate canbe substrate 202 in FIG. 2. The dielectric layer can be formed usingsilicon oxide, silicon nitride, silicon oxynitride, and/or othersuitable dielectric materials. A plurality of conductor layer anddielectric layer pairs are formed in a staircase region and an activedevice region of the 3D NAND memory structure. In some embodiments, thealternating conductor/dielectric stack includes more conductor layers ormore dielectric layers with different materials and/or thicknesses thanthe conductor/dielectric layer pair. The conductor layers can include,W, Co, Cu, Al, doped silicon, silicides, or any combination thereof. Thedielectric layers can include silicon oxide, silicon nitride, siliconoxynitride, or any combination thereof. 3D NAND memory device furtherincludes NAND strings formed in the active device region and include aplurality of control gates. A peripheral device region can include aplurality of peripheral devices formed on the substrate. The peripheraldevices can include a plurality of transistors formed on the substrate.Isolation regions and doped regions can also be formed in the substrate.Sacrificial regions can be formed adjacent to the device regions. Insome embodiments, sacrificial regions can be a scribe line between eachdie of an array of dies for allowing a dicing saw to cut through andseparate the dies. Examples of sacrificial regions can be sacrificialregions 250 described in FIG. 2.

At operation 1104, one or more openings are formed in sacrificialregions, in accordance with some embodiments. In some embodiments,openings are also formed in device regions, for example, one or morevias are formed in the staircase region, the active device region, andthe peripheral device region. In some embodiments, the one or moreopenings in the sacrificial regions can extend through the dielectriclayer and into the substrate. In some embodiments, the one or moreopenings in the sacrificial regions can have a trapezoidalcross-sectional shape with a wider top portion and a narrower bottomportion. In some embodiments, the one or more openings in thesacrificial regions can have a trapezoidal cross-sectional shape with anarrower top portion and a wider bottom portion. Examples of forming oneor more openings in the sacrificial regions can be the processes used toform openings 252 in FIG. 2.

At operation 1106, high-stress material is disposed in the one or moreopenings in the sacrificial regions, in accordance with someembodiments. In some embodiments, high-stress material with compressivestress can be disposed to reduce tensile stress in the semiconductorwafer. In some embodiments, high-stress material with tensile stress canbe disposed to reduce compressive stress in the semiconductor wafer.High-stress material can be disposed into the one or more openings inthe sacrificial regions and also the openings in the device region. Thedeposition processes can include any suitable methods such as CVD, PVD,PECVD, sputtering, MOCVD, ALD, and/or combinations thereof. Thehigh-stress material can be disposed until the one or more openings arecompletely filled with high-stress material. In some embodiments, thehigh-stress material is also an electrically conductive material thatcan also provide electrical connectivity. For example, the high-stressmaterial can be tungsten. In some embodiments, the high-stress materialcan overflow onto a top surface of the dielectric layer. Examples ofhigh-stress material disposed in the openings can be high-stressmaterial 310 described in FIG. 3.

At operation 1108, the disposed high-stress material is planarized toform counter-stress structures, in accordance with some embodiments. Aplanarization process can be used to remove excessive disposedhigh-stress material from a top surface of the dielectric layer suchthat top surfaces of the high-stress material filled in the openings ofdevice regions and sacrificial regions are substantially level with thetop surface of the dielectric layer. In some embodiments, theplanarization process can be a chemical mechanical polishing process.After the planarization process, conductive structures are formed in theopenings of the device region and counter-stress structures are formedin the sacrificial region. Examples of conductive structures can beconductive structures 412 and conductive structures 432 described inFIG. 4. In some embodiments, the conductive structures can be contactwires and referred to as word line contacts. Examples of counter-stressstructures can be counter-stress structures 452 formed in thesacrificial region after the planarization process. Examples ofcounter-stress structures can also be counter-stress structures 652,752, 804, 809, 810 x, and 810 y described in FIGS. 6-10.

At operation 1110, additional structures such as additional dielectriclayers and lead wires are formed on the semiconductor structure, inaccordance with some embodiments. For example, additional dielectriclayers can be disposed on the planarized top surface of the dielectriclayer that includes the counter-stress structures. The additionaldielectric layer can also be disposed on top surfaces of the conductivestructures and counter-stress structures. The additional dielectriclayer can be formed using any suitable dielectric material such as, forexample, silicon oxide, silicon nitride, silicon oxynitride, and/orother suitable dielectric materials. The deposition of additionaldielectric layer can include any suitable methods such as CVD, PVD,PECVD, sputtering, MOCVD, ALD, and/or combinations thereof.

Various embodiments described herein are directed to counter-stressstructures of a 3D NAND memory device and fabricating methods of thesame. The exemplary fabrication method includes forming openings insacrificial regions of a semiconductor wafer. In some embodiments, thesemiconductor wafer contains an array of 3D NAND memory devices and thesacrificial regions are scribe lines between the 3D NAND memory devices.High stress material is disposed in the openings and used to counter thestress formed by other structures on the semiconductor wafer. In someembodiments, forming the openings and depositing high stress materialcan be performed concurrently with forming openings for peripheralcircuitry and depositing conductive material in the peripheral circuitopenings, respectively, providing the benefit of no additional masks orprocesses steps. In some embodiments, the counter-stress structures canbe trenches filled with high-stress material and formed in sacrificialregions such as scribe lines that are located between adjacent activeregions of the semiconductor wafer. In some embodiments, thecounter-stress structures can be formed along the x-direction or they-direction. In some embodiments, the dimension and density ofcounter-stress structures can be determined by the stress level of thesemiconductor wafer. Counter-stress structures can provide benefits suchas, among other things, reduced stress in 3D NAND memory devices withoutoccupying device space, no additional masks or processing steps, andwide range of suitable high-stress materials. Therefore, counter-stressstructures can reduce stress in semiconductor wafers, which in turnensures and improves the performance and yield of the 3D NAND memorydevices.

The foregoing description of the specific embodiments will so fullyreveal the general nature of the present disclosure that others can, byapplying knowledge within the skill of the art, readily modify and/oradapt for various applications such specific embodiments, without undueexperimentation, without departing from the general concept of thepresent disclosure. Therefore, such adaptations and modifications areintended to be within the meaning and range of equivalents of thedisclosed embodiments, based on the teaching and guidance presentedherein. It is to be understood that the phraseology or terminologyherein is for the purpose of description and not of limitation, suchthat the terminology or phraseology of the present specification is tobe interpreted by the skilled artisan in light of the teachings andguidance.

Embodiments of the present disclosure have been described above with theaid of functional building blocks illustrating the implementation ofspecified functions and relationships thereof. The boundaries of thesefunctional building blocks have been arbitrarily defined herein for theconvenience of the description. Alternate boundaries can be defined solong as the specified functions and relationships thereof areappropriately performed.

The Summary and Abstract sections may set forth one or more but not allexemplary embodiments of the present disclosure as contemplated by theinventor(s), and thus, are not intended to limit the present disclosureand the appended claims in any way.

The breadth and scope of the present disclosure should not be limited byany of the above-described exemplary embodiments, but should be definedonly in accordance with the following claims and their equivalents.

What is claimed is:
 1. A semiconductor wafer comprising: a substratehaving a dielectric layer formed thereon; a device region in thedielectric layer and comprising at least one semiconductor device; asacrificial region adjacent to the device region; and at least onecounter-stress structure in the sacrificial region, wherein the at leastone counter-stress structure comprises tungsten and is configured tocounteract wafer stress formed in the device region.
 2. Thesemiconductor wafer of claim 1, wherein the at least one counter-stressstructure comprises high-stress material.
 3. The semiconductor wafer ofclaim 1, wherein the at least one counter-stress structure is formed inthe dielectric layer and extends into the substrate.
 4. Thesemiconductor wafer of claim 1, wherein a width of the at least onecounter-stress structure is between about 0.1 μm and about 0.5 μm and adepth of the at least one counter-stress structure is between about 4 μmand about 10 μm.
 5. The semiconductor wafer of claim 1, wherein thewafer stress formed in the device region is compressive and the at leastone counter-stress structure is configured to produce tensile stress. 6.The semiconductor wafer of claim 1, wherein the water stress formed inthe device region is tensile and the at least one counter-stressstructure is configured to produce compressive stress.
 7. Thesemiconductor wafer of claim 1, wherein the sacrificial region comprisesa scribe line of the semiconductor wafer.
 8. The semiconductor wafer ofclaim 1, wherein the device region comprises a three-dimensional (3D)memory structure.
 9. The semiconductor wafer of claim 1, wherein thedevice region comprises a peripheral device.
 10. The semiconductor waferof claim 1, further comprising an another dielectric layer disposed ontop surfaces of the at least one counter-stress structures.
 11. Asemiconductor water comprising: an array of dies, wherein each die ofthe array of dies comprises a first type of wafer stress; sacrificialregions between adjacent dies of the array of dies; and a plurality ofsemiconductor structures formed in the sacrificial regions, wherein eachsemiconductor structure comprises tungsten and is configured to producea second type of wafer stress to counteract the first type of waferstress.
 12. The semiconductor wafer of claim 11, wherein the first andsecond types of wafer stress comprise compressive and tensile waferstress, respectively.
 13. The semiconductor wafer of claim 11, whereinthe first and second types of wafer stress comprise tensile andcompressive wafer stress, respectively.
 14. The semiconductor wafer ofclaim 11, wherein the each die of the array of dies comprises athree-dimensional (3D) memory structure.
 15. The semiconductor wafer ofclaim 11, wherein the sacrificial regions comprises scribe lines of thesemiconductor wafer.
 16. A method for forming a semiconductor wafer, themethod comprising: forming a dielectric layer on a substrate; forming aplurality of semiconductor structures in a device region of thesemiconductor wafer, wherein the plurality of semiconductor structuresproduce a first type of wafer stress in the semiconductor wafer; forminga first plurality of openings in the dielectric layer and in the deviceregion; forming a second plurality of openings in the dielectric layerand in a sacrificial region that is adjacent to the device region; anddisposing high-stress material in the first and second pluralities ofopenings, wherein the disposed high-stress material produces a secondtype of wafer stress in the semiconductor wafer to counteract the firsttype of wafer stress.
 17. The method of claim 16, wherein disposing thehigh-stress material comprises disposing tungsten.
 18. The method ofclaim 16, wherein disposing the high-stress material is performed usingone of chemical vapor deposition (CVD), physical vapor deposition (PVD),plasma-enhanced CVD (PECVD), sputtering, metal-organic chemical vapordeposition (MOCVD), or atomic layer deposition (ALD).
 19. The method ofclaim 16, further comprising planarizing the disposed high-stressmaterial and the dielectric layer.
 20. The method of claim 16, whereinforming the plurality of semiconductor structures comprises formingthree-dimensional (3D) memory structures.
 21. The method of claim 16,further comprising disposing an another dielectric layer on top surfacesof the disposed high-stress material.
 22. The method of claim 16,further comprising dicing the semiconductor wafer through thesacrificial region.